This invention relates generally to improvements in the design and construction of diaphragm sealed pumps and metering devices by the incorporation of a helix within a tubular diaphragm to achieve continuous fluid flow, and more specifically to employing differing diameters in the pump bore and differeing helix configurations to achieve differential fluid flows to satisfy special requirements.
In accordance with this invention, a tubular diaphragm which is circumferentially deformable and having an inside diameter which is smaller than the minor diameter of a given helix is mounted in a bore of a pump casing with the ends of the tubular diaphragm attached to the pump casing. At least one longitudinal rib of the tubular diaphragm is continuously attached along its length to the pump casing. The bore in the pump casing in which the tubular diaphragm is located may have one or more diameters along its length. A minimum of two fluid passageways through the pump casing provide communication from some external supply of the fluid to be pumped with a volume between the tubular diaphragm and the pump casing, and from the volume between the pump casing and the tubular diaphragm to some external point of use, such fluid passageways generally located at either end of the tubular diaphragm near the points of attachment to the pump casing. Additional fluid passageways between some external points and the volume between the tubular diaphragm and the pump casing are provided at each instance of the change in diameter of the circular bore of the pump casing or the change in configuration of the helix causing pumping action. A helix with a major diameter of such dimensions as to cause the tubular diaphragm to contact and form a fluid seal with the wall of the bore of the pump casing along the ridge line of the helix is mounted within the pump casing and tubular diaphragm. A finite volume cavity is thereby formed by the bore wall of the pump casing, the tubular diaphragm from the point of contact and fluid seal with the bore wall from one ridge of the helix to the next successive ridge of the helix, and from one longitudinal rib of the diaphragm to the next successive longitudinal rib which could also be the opposite side of the original longitudinal rib, such rib being continuously attached along its length to the pump casing and acting to prevent the uncontrolled flow of fluid during the pumping action caused by the rotation of the helix. The fluid cavity thus defined progresses longitudinally along the bore of the pump casing due to the rotation of the helix thereby conveying the fluid being pumped. The end connections of the tubular diaphragm with the pump casing prevent further longitudinal movement of the fluid conveyed in the travelling cavity, and such fluid is appropriately discharged or drawn into the cavity depending upon the direction of rotation of the helix.
The volume of the fluid cavity as defined above may be varied by changing any of several cavity parameters which include the diameter of the bore, the thickness of the wall of the tubular diaphragm, the major diameter of the helix, the minor diameter of the helix, or the pitch distance between the ridge lines of the helix. In addition, more than one longitudinal rib of the tubular diaphragm may be employed thereby increasing the number of separate and distinct fluid flow channels that may be used and concurrently reducing the volume of each of the fluid flow channels.
In the preferred form of the invention as shown in the drawing, the flow of up to four different fluids is controlled by changing both the diameter of the bore of the pump casing and the diameters of the helix to provide for the introduction, mixing and discharge of metered amounts of fluids into the initial flow stream and the eventual discharge of all fluids from the pump.
In other forms of the invention, the fluid flow channels defined by the bore wall, tubular diaphragm and diaphragm ribs may be of different number and dimensions so as to achieve proportional flows of different fluids.
In still other forms of this invention, further variations and changes in bore diameters, diaphragm thicknesses, and helix configurations may be used to achieve specific fluid flow conditions in one or more fluid channels.
In still further forms of this invention, double or triple helixes may be employed instead of the single helix shown in the drawing to achieve specific fluid flow conditions, and the position of the tubular diaphragm with respect to the helix and the bore wall of the pump casing may be varied to achieve varied flow during the operation of the pump.
The principal objective of this invention is to provide a diaphragm sealed pumping device capable of achieving the continuous flow of fluids and the elimination of auxiliary flow control devices such as check valves.
A more specific object of this invention is to provide a pumping device in which several different fluids may be differentially ingested, mixed, metered, and discharged as required for specific operating purposes.
It is another object of this invention to provide a pumping device capable of handling metered quantities of more than one fluid each in separate channels concurrently.
It is a further object of this invention to provide a simple diaphragm sealed pumping device to handle extremely small flows of different fluids in such a manner that metered quantities of other fluids such as diluents or reagents may be added to the initial base fluid or their volume otherwise changed in the course of moving the fluids through the pumping device.
Other objects and advantages of the invention will become apparent upon full consideration of the following description and the attached drawing.